okie981

Thanks! Will do.

Voyager6

I believe the discrepancy in the Clutch fluid fill amount is that the clutch retains about half its volume. Obviously, you can fill and run a short while to mix the fluid and then change a second time. That should get you to below 20 percent old fluid left over. But at $20+/L, that can get pricey.

I bought gear and clutch oil for both my 2014 981s iand will change n the next few weeks, I bought the Driven gear oil and Pentosin FFL3 clutch fluid.

V6

splinterAMG

Thank you!

okie981

Here are the results from SpeedDiagnostix for my new/old PDK clutch side oil analysis. Note this is from my car I've owned since brand new, 32k+ miles and 12 track days on the old oil. I used OEM for the new fluid fill and sample, so this is OEM to OEM fluid comparison. The dealer did the drain, did not pull the pan or swap the filter. They charged me for 3 quarts of refill, so I assume that's what I got. Total clutch-side fluid capacity per a Porsche SIT document I found online somewhere is 5.7 quarts in the CG2.25 PDK that is installed in all 981 S model cars. Bottom line, no definitive conclusions can be made about anything detrimental going on until a trend is established. Lake Speed Jr. and I discussed the results over a phone call yesterday. I can say the car shifts beautifully, hot or cold, being driven like grandma or like hell. On track at 95 degree ambient temps at the end of a 20 minute session, the shifts are fast and firm with no clutch slip that I can detect. This 3 liter drain and refill was done for precautionary maintenance reasons only. I will do again after 10 total track days (already done 2 on this 3 liter fluid refill, so 8 to go). For reference, I have had the 3rd radiator installed for 5 of the 12 track days on this PDK clutch fluid drain. For those 7 days without the 3rd radiator, only 1 of them was at 90+ deg. ambient temp.

Charles Navarro

Thanks for sharing this. Great stuff. Nothing works better than real world testing and real world results, so I'm looking forward to seeing the UOA results on future fills to come up with trending data for the PDK.

981KMAN

@PorscheAddict. Thank you for this excellent write up with pictures. They are greatly appreciated. I have a question;

Why did you drain the Gear Oil from 2 different plugs? One under the Differential, and a larger plug under the Gear Set. Since they both fill from the same side fill port, would draining from the lower Differential plug work just as well?

Thanks so much!

Take care

981KMAN

--

PorscheAddict

My understanding is that you have to remove both plugs to drain the maximum amount of fluid. There may be baffling or something else preventing all of the fluid from going to the rear-most plug. It doesn't take much effort at all to remove both, so just do both. Make sure the car is level. Good luck!

okie981

Yes, this.

981KMAN

Thanks for the quick reply, sounds reasonable. I ask, as I just had my PDK Serviced at the dealer, for fluid/oil replacement on both the Clutch and the Gear Set, Yet the larger Gear Set Drain plug does not look like it was removed and there is no oil residue or wipe down of the surrounding area. So I do not think this plug was removed.

Actually the Fill Plug and the smaller Drain plug by the Pan look like they have not been removed either? Must talk with Dealer as service may have been skipped?


PDK Differential Drain Plug (small M10 X 1)

Hard to tell if this plug has been removed or not?? What do you think?

PorscheAddict

You are not necessarily going to be able to tell if a particular bolt or plug has been removed and reinstalled if they cleaned the area afterward. I wouldn't worry about it.

Noah Fect

If they cleaned the area afterward, it would obviously look like it had been cleaned, no?

PorscheAddict

No. I always wipe off excess with a rag, and sometimes hit it with Brakleen or something, but it may not remove years of discoloration etc. Mine was not obvious after the fluid change.

981KMAN

So in prep for changing the Gear Oil in my PDK tranny, I have been looking at the specification of the OE oil (Mobilube PTX 75W-90), and trying to find a GL-5 rated gear oil with similar or better specifications.

Here is the Original Equipment oil Mobilube PTX 75W-90;

The significant information with the OE oil is the Low Temp Viscosity of 77.6 cSt @40C. Most of the other 75W-90 GL-5 gear oils have a much higher Low Temperature Viscosity in the range of 110 - 120 cSt.
This is important to maintain easy/smooth shift performance during cold starts, especially in colder weather. (for those of us that drive our Porsches year round)

I finally found what appears to be a suitable replacement, with similar, and possibly better Viscosity specs: Motul Gear 300 75W-90

Motul Gear 300 75W-90 is a GL-5 rated full synthetic oil


So the Low Temperature Viscosity is less than the Mobilube, and the High Temperature Viscosity is higher than the Mobilube's. Which is what I feel is desired.

I have found the Motul is available from several sources online for around $21.00 per liter. Which is better than the $30.00 per liter for the Mobilube from Sunset Porsche.

Has anyone used the Motul Gear 300 75W-90 in their transmission? Any other comments or input (Positive or Negative)?

Thanks in advance.